This study aimed to improve students’ self-esteem towards mathematics learning in MTs Ummul Quro through cooperative learning of Students Team Achievement Divisions (STAD). This was a classroom action research study and the research subjects were thirty one students of Grade IX B. The data as indicators of the success of class actions were collected using a self-esteem questionnaire for mathematics learning, mathematics learning achievement tests, and observation sheets for the implementation of STAD cooperative learning. In the implementation, the results showed that in Cycle I there were still students who had low self-esteem, 67.74% of students attained the minimum mastery criterion (MMC), and the percentage of the implementation of STAD cooperative learning was 85.33%. In Cycle II, no students had low self-esteem, 77.42% of students attained the MMC, and the percentage of the implementation of STAD cooperative learning was 96.67%. In general, the results of the study showed that STAD cooperative learning could improve the self-esteem of Grade IX B of MTs through two cycles.